1. Field of the Invention
The present invention is directed to a gas humidifying device for humidifying gases which are supplied to a fuel cell in which an anode electrode and a cathode electrode are disposed in facing relation to each other with an electrolyte membrane interposed therebetween.
2. Description of the Related Art
There have been developed fuel cells comprising, for example, a plurality of stacked fuel cell units each having an anode and a cathode provided in opposing relation with an ion exchange membrane sandwiched therebetween, the fuel cell units further being interposed between separators. Such fuel cells are being put to practical use in a variety of applications.
Such types of fuel cells, for example, are structured such that a hydrogen gas (i.e. a fuel gas) which is generated by methanol vapor reforming is supplied to an anode electrode, and an oxygen-containing gas (air) is supplied to a cathode electrode, whereby the hydrogen gas becomes ionized and flows through a solid polymer electrolyte membrane, thereby generating electrical energy out of the fuel cell.
In this case, in order that efficient generation of electrical power from the fuel cell can be exhibited, it is necessary to maintain the solid polymer electrolyte membrane in an optimal humidified state. For this purpose, it has been known to provide a humidifying device for humidifying in advance by water the fuel and oxygen-containing gases, and by constructing the humidifying device and fuel cell to be connected to each other, humidified fuel and oxygen-containing gases are supplied to the fuel cell unit.
However, with a humidifying device as described above, especially when used in regions having particularly cold climates, it is often the case that the water which is used for humidification tends to become frozen. Due to this problem, before initiating operation of the fuel cell, it is necessary to perform a melting operation on the water contained in the interior of the humidifying device, and such an operation is both troublesome and time consuming.
The present invention has the object of addressing and solving the aforementioned problems, wherein a melting operation for water inside a humidifying device can be easily and swiftly carried out, yet while offering a humidifying device for humidifying gases in a fuel cell having a simplified structure.
In order to address these problems, it is an object of the present invention to provide a humidifying device for humidifying gases in a fuel cell, in which a gas supply passage is formed on one side surface of a water permeable element, a humidifying water passage is formed on the other side surface of the water permeable element, and a medium flow passage is disposed in proximity to the humidifying water passage. In addition, the fuel and oxygen-containing gases are supplied to respective gas supply passages, whereas water is supplied to the humidifying water passage, and such water permeates the water permeable element, so that the gases in the gas supply passages are effectively humidified.
When water becomes frozen in the water supply passage, because a medium having a melting point lower than that of water is supplied to the medium flow path which is disposed in proximity to the humidifying water passage, heat exchange occurs between the water and the medium, and the water can be easily and reliably melted. Notwithstanding, not only is such a medium flow passage provided, but also the overall structure of the humidifying device can be effectively simplified.
For this purpose, a heating means is disposed in a circulatory route for circulating the medium to the medium supply passage. Accordingly, because the medium is heated by the heating means, a melting operation on the water can be even more swiftly and reliably accomplished.
Further, a first circulatory path for supplying the medium to a cooling passage in the interior of the fuel cell, and a second circulatory path for circulating the medium to the medium passage in the interior of the humidifying means are provided, wherein when water becomes frozen inside the humidifying means, the medium is supplied to the second circulatory path via a switching valve means. As a result, the structure of the humidifying means is simplified.
The above and other objects, features and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which preferred embodiments of the present invention are shown by way of illustrative examples.